1. Field of the Invention
The invention relates to a driving apparatus, a driving method, and a touch sensing system. More particularly, the invention relates to a sensing and driving apparatus and a sensing and driving method used in a touch sensing system.
2. Description of Related Art
At present, the touch panels can be generally classified into resistive, capacitive, infrared, and ultrasonic touch panels, wherein the resistive touch panels and the capacitive touch panels are most common. Compared with the resistive touch panels which can only detect the operation of an user when the panel is pressed by the user, the capacitive touch panels can easily detect the operation of an user when the user's finger touches the panel or is suspended over the panel. In the conventional art, the capacitive touch panels detect a voltage change in sensing lines to obtain touch information of a single point or two points.
FIG. 1 illustrates a voltage waveform of a sensing line before and after the sensing line is touched. Before the sensing line is touched, the sensing circuit is required to store the voltage value V of the sensing line which serves as a baseline. Then, the actually measured voltage value V′ is compared with the baseline so as to obtain a voltage change ΔV corresponding to the sensing line. As shown in FIG. 1, in addition to the voltage change ΔV of the sensing line, a common mode voltage also exists at the sensing side, which equals to voltage value V. Since an offset of an output voltage of the sensing circuit occurs due to the common mode voltage, the degree of sensitivity of the sensing circuit is reduced.